Diffusion transfer product with microcapsules containing glycerin-water solutions



Feb. 28, 1967 H. c. HAAS 3,306,747

DIFFUSION TRANSFER PRODUCT WITH MICROCAPSULES CONTAINING GLYCERINWATER SOLUTIONS Filed Dec. 26, 1962 INVENTOR.

BY W

ATTORNEYS United States Patent 3,306,747 DIFFUSION TRANSFER PRODUCT WITH MICRO- CAPSULES CONTAINING GLYCERIN -WATER SOLUTIONS Howard C. Haas, Arlington, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Dela- Ware Filed Dec. 26, 1962, Ser. No. 246,930 6 Claims. (CI. 9676) This invention relates to photography and more particularly to products, processes and compositions for the development of photosensitive silver halide emulsions.

One object of this invention is to provide a novel composition for the development of silver halide emulsions.

Another object is to provide a novel silver halide developer composition which is enclosed in minute, pressure-rupturable capsules.

Another object is to provide a novel photographic product containing a layer of minute, pressure-rupturable 'cap-. sules containing silver halide developer compositions.

Still another object of this invention is to provide novel processes for developing a photosensitive silver halide emulsion containing a layer of minute, pressure-rupturable capsules containing a novel silver halide developer composition.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the process in-v volving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, prop erties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

FIG. 1 is an enlarged, diagrammatic, sectional view of a photographic product comprehended by this invention;

FIG. 2 is a view similar to FIGURE 1 of another embodiment of a product of this invention; and

FIG. 3 is a fragmentary, diagrammatic view of means for processing the product of this invention by rupturing the layer of capsules with an image-receiving sheet in superposed relation to the said novel product.

US. Patent No. 2,543,181, issued February 27, 1951, to Edwin H. Land, discloses frangible containers carrying a photographic processing liquid used in developing exposed photosensitive emulsions. In one embodiment, such frangible containers may be in the form of a packet or pod which, when ruptured, will release a fairly thin layer of processing fluid over a fairly large surface area. The processing fluid is released at the edges of the superimposed photosensitive sheet and image-receiving element and is spread therebetween. Such a container is of such size and bulk that it may impart some degree of deformation in the photographic product with which it is associated. The necessity of providing a container-fabricated of materials which are impervious to the contents, waterimpermeable and of sufl'lcient size to contain sufiicient processing fluid is responsible for the size and bulk of the containers. When a layer of cell-like chambers or sacs located in an area coexistent with the emulsion layer is utilized to carry the processing composition, the problem of bulk is eliminated but the problem of selection of materials and manufacture of the chambers or sacs to provide uniform air and water impermeability becomes more acute. The openings through which the processing composition is expelled are particularly vulnerable to air and moisture passage.

3,306,747 Patented Feb. 28, 1967 The objects of this invention, therefore, are to provide a photographic composition which will be more stable than prior art compositions due to a substantially decreased tenden-cy to lose water, thereby minimizing the problem of moisture permeability of the containers, and to provide containers for said processing composition which are minute in size and which may be incorporated in a layer in the photosensitive element which contains the photosensitive silver halide emulsion, thereby obviating the problem of deformation of the photographic product associated with the containers.

It is known that glycerin will absorb and hold tonaciously a certain percentage of its weight of water, with the percentage of water absorbed and held dependent upon the relative humidity of the environment. For example, at a relative humidity of 60%, glycerin will hold 40% of its weight of water. Methods are known to the art whereby either glycerin or water may be encapsulated in minute, pressure-rupturable capsules. However, since water is such a small molecule, it readily passes through the polymeric wall of the capsule. Glycerin, on the other hand, is a larger molecule with a much lower vapor pressure and therefore it would diffuse at a much slower rate through the capsule walls.

It is proposed to utilize the above-described phenomena to provide the novel photographic processing composition of this invention, comprising a glycerin-water solution, to process exposed silver halide emulsions comprising colloid binders which are swellable by both water and glycerin. The novel photographic processing com, position of this invention possesses a high degree of stability in that, when encapsulated in pressure-rupturable capsules, the composition will hold a designated quantity of water at a predetermined level of relative humidity of the environment. Water will be lost only when said relative humidity drops, and even then the loss will be at a very slow rate. Further, as the relative humidity again rises to predetermined level, the encapsulated composition has the ability to reacquire the lost moisture.

By means of this invention, it is possible to provide a high degree of shelf-life stability to a photographic product comprising an image-receiving element and a photo.- sensitive element comprising a silver halide emulsion and a layer of capsules containing the photographic processing composition of this invention, whereby the image is produced on the image-receiving element by the diffusion transfer process, such as is disclosed in the above-cited US. Patent No. 2,543,181, and, at the same time, minimize disadvantages existing in the prior art.

Alkali, silver halide developing agents, silver halide solvents, and other additives necessary for photographic processing may be added as desired to the glycerin-water solution. The processing composition may then be encapsulated in minute, pressure-rupturable capsules by methods known to the art.

The novel processing composition of this invention may be utilized in a photographic element comprising a support, a layer of the microscopic pressure-rupturable cap sules containing said photographic processing composition, and a silver halide emulsion layer. After the silver halide emulsion has been exposed to an image, an image-receiving element is superposed over the exposed emulsion layer and pressure applied to the unit. The capsules will rupture and permit the processing composition to permeate the exposed photosensitive layer, developing the exposed silver halide. The nonexposed silver halide is transferred from the photosensitive layer to the adjacent image-receiving layer where it is precipitated to provide a positive silver transfer image.

In another embodiment of this invention, in order to further lessen the possibility of oxygen attacking the silver halide developing agent in the capsule, the sliver halide developing agent may be contained in a water-soluble polymer layer which may then be placed in an appropriate position in the photosensitive element, e.g., next to the capsule layer containing the remainder of the processing ingredients or, alternatively, in a layer next to the image-receiving element. Upon processing, the ruptured capsules will release the processing composition and the water contained therein will dissolve or swell the polymer releasing the silver halide developing agent and thereby accomplishing development of the latent image.

Referring to FIGURE 1, there is illustrated diagrammatically one embodiment of the novel photographic product of this invention which, as shown, comprises a suitable support 10, such as paper, or plastic, such as cellulose acetate, a capsule layer 11 comprising minute, pressure-rupturable capsules containing a photographic processing composition comprising a glycerine-water mixture and a layer 12 of a photosensitive silver halide emulsion,

.said layers superimposed on the support in the order named.

FIG. 2 shows an alternate embodiment of the novel product of this invention which, as shown, comprises a support 10, a capsule layer 11 comprising minute, pressure-rupturable capsules containing a photographic processing composition without a silver halide developing agent, a layer 12 of a photosensitive silver halide emulsion, a layer 16 comprising a water-soluble polymeric stratum containing a silver halide developing agent,-said layers being superimposed upon the base in the order named. Alternatively, the layer 16, comprising the watersoluble polymeric stratum, may be placed next to the layer 11.

Referring to FIG. 3, which discloses one method of processing the novel photographic product of this invention, wherein a layer 12, adapted to receive a silver transfer image, is placed in superposed relation to a photographic product comprising a support 10, a capsule layer '11 comprising minute, pressure-rupturable capsules containing a photographic processing composition, and a layer 12 of a photosensitive silver halide emulsion, said layers superimposed on the support in the order named and the image-receiving layer 14 is contiguous to the silver halide emulsion layer 12, said superimposed layers are inserted between pressure rollers 15 whereby the capsules in capsule layer 11 are ruptured releasing the photographic processing composition wherein which permeates said layer 12 developing the latent image therein and providing a positive of said developed image on said imagereceiving layer 14. The image-receiving layer 14 containing the positive image mayvthen be stripped from contact with the emulsion layer 12.

In order to speed the time of processing, the silver halide emulsion colloid binder is preferably one which is readily wet and swelled by the glycerin-water solution. The preferred emulsion is a hydroxyethyl-polyvinyl alcohol-silver halide emulsion such as that described and claimed in the copending US. application of W. H. Ryan, Serial No. 170,008, filed January 31, 1962. However, any other colloid binders known to the art may be used provided they are swellable by the glycerin-water solution.

As stated above, the novel photographic processing compositions of this invention may be encapsulated by methods known to the art. As examples of suitable encapsulating material, mention may be made of polystyrene, epoxy resins and vinylidene chloride/vinyl chloride copolymers, such as those sold by Dow Chemical Company, Midland, Michigan, under the trade name Saran.

A particularly useful novel processing composition of this invention comprises:

Glycerin cc 30 Water cc 20 Sodium hydroxide (50% aqueous solution) gm Hydroquinone gm 2 Sodium thiosulfate gm 1.5

The composition was saturated with sodium sulfite.

Using the above processing composition, a silver trans-' fer image was formed in 2 minutes by developing an exposed hydroxyethyl-polyvinyl alcohol silver halide emulsion and transferring unexposed silver halide to a superposed silver-receptive image-receiving sheet.

The novel photographic processing composition of this invention is preferably contained in pressure-rupturable capsules which may best be described as minute in size: The capsules should be large enough to provide a practical ratio of contents to wall material but should be small enough to eliminate any appreciable adverse effects on the negative and the resulting positive image. Capsules ranging from 5 to 125 microns in size are found to be satisfactory.

By means of this invention, it is possible to provide a photographic product comprising a plurality of photosensitive elements which may be rolled or stacked together without any distortion or deformation of the elements resulting from the association of a packet containing processing fluid, and to provide a photographic processing composition which will provide a low susceptibility to water loss due to the moisture permeability of the container wall, thereby avoiding the resultant deterioration of the processing composition due to water loss. This invention makes it possible to process diffusion transfer negatives with a novel processing composition incorporated into said negative in a plurality of containers which are small enough to be incorporated into a layer in said negative without adversely affecting the photographic properties and in a manner which will insure stability of the composition,

While the novel products, processes and compositions of this invention have been illustrated in silver halide transfer processes, it should be understood that the invention is not limited and may be applied to color transfer processes, such as those set forth in US. Patent No. 2,983,606, issued May 9, 1961, to Howard G. Rogers.

The photographic products within the scope of this invention may be used in roll film units which contain a plurality of photo-sensitive frames. The photographic products of this invention are especially useful in composite roll film intended for use in a Polaroid Land Camera, sold by Polaroid Corporation, Cambridge 39, Massachusetts, or a similar camera structure such, for example, as the camera forming the subject matter of U8. Patent No. 2,435,717, issued to Edwin H. Land on February 10, 1958.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A photographic product comprising a plurality of layers-including a support, a layer on said support com prising microscopic pressure-rupturable capsules containing a photographic processing composition including a. glycerin-water solution containing a silver halide proc essing reagent selected from the group consisting of a. silver halide photographic developing agent and a silver halide solvent, a layer on said support comprising a silver halide emulsion.

2. A photographic product as defined ,in claim 1, wherein said processing composition includes alkali.

3. A photographic product as defined in claim 1, wherein said microscopic pressure-rupturable capsules range from about 5 to microns in size.

4. A photographic product as defined in claim 1, wherein said glycerin-water solution comprises about 40% water by Weight.

5. A photographic product as defined in claim 1, wherein said silver halide developing agent is hydroquinone.

5 6. A photographic product as defined in claim 1, wherein said layer comprising microscopic pressurerupturable capsules is positioned intermediate said support and a layer comprising a silver halide emulsion.

References Cited by the Examiner UNITED STATES PATENTS 2,299,694 10/1942 Green 106-236 X 2,800,457 7/1957 Green et a1. 252-316 2,971,840 2/1961 Haydn et a1. 9629 3,019,124 1/1962 Rogers 963 6 3,111,407 11/1963 Lindquist et a1. 9676 XR 3,212,896 10/ 1965 Yudelson et a1. 9676 XR FOREIGN PATENTS 5 821,506 10/1959 Great Britain.

OTHER REFERENCES Varden: Modern Photography, page 86 (1958).

10 I. TRAVIS BROWN, Primary Examiner.

DONALD LEVY, Examiner. 

1. A PHOTOGRAPHIC PRODUCT COMPRISING A PLURALITY OF LAYERS INCLUDING A SUPPORT, A LAYER ON SAID SUPPORT COMPRISING MICROSCOPIC PRESSURE-RUPTURABLE CAPSULES CONTAINING A PHOTOGRAPHIC PROCESSING COMPOSITION INCLUDING A GLYCERIN-WATER SOLUTION CONTAINING A SILVER HALIDE PROCESSING REAGENT SELECTED FROM THE GROUP CONSISTING OF A SILVER HALIDE PHOTOGRAPHIC DEVELOPING AGENT AND A SILVER HALIDE SOLVENT, A LAYER ON SAID SUPPORT COMPRISING A SILVER HALIDE EMULSION. 